Vertical batch furnace assembly comprising a cooling gas supply

ABSTRACT

A vertical batch furnace assembly, comprising a core tube, an outer casing, a cooling chamber bounded and enclosed by the outer casing and the core tube, and at least one cooling gas supply emanating in the cooling chamber. The core tube has an elongated circumferential wall extending in a longitudinal direction, and is configured to accommodate wafers for processing in the vertical batch furnace. The outer casing extends around the core tube and comprises a heating element for applying a thermal treatment to wafers accommodated in the core tube. The at least one cooling gas supply comprises at least one cooling gas supply opening which is arranged such that the cooling gas enters the cooling chamber with a flow direction which is substantially tangent to the circumferential wall.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patent application Ser. No. 17/236,065 filed Apr. 21, 2021 titled VERTICAL BATCH FURNACE ASSEMBLY COMPRISING A COOLING GAS SUPPLY, which claims the benefit of U.S. Provisional Patent Application Ser. No. 63/014,993 filed Apr. 24, 2020 titled VERTICAL BATCH FURNACE ASSEMBLY COMPRISING A COOLING GAS SUPPLY, the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a vertical batch furnace assembly comprising a cooling gas supply.

BACKGROUND

Most vertical batch furnaces are provided with a core tube configured to accommodate wafers to be processed in the vertical batch furnace. During a treatment in the vertical batch furnace the wafers and core tube may get hot. In order to speed up the throughput of the vertical batch furnace assembly, the core tube may be cooled down. Cooling gas may be supplied from a number of circumferentially spaced openings at a lateral side of a cooling chamber between the circumferential wall of the core tube and an outer casing.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form. These concepts are described in further detail in the detailed description of example embodiments of the disclosure below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

It may be realized that circumferentially spaced openings may locally produce cold spots on the circumferential wall of the core tube. Such cold spots may cause temperature differences within the circumferential wall, which may lead to stresses in said circumferential wall. Furthermore, the wafers inside the core tube may also be exposed to temperature differences which may lead to breaking of said wafers.

Therefore, it may be an object to provide a vertical batch furnace assembly in which the above mentioned problems may be alleviated.

To that end, there may be provided a vertical batch furnace assembly according to claim 1. More particularly, there may be provided a vertical batch furnace assembly comprising a core tube, an outer casing, a cooling chamber bounded and enclosed by the outer casing and the core tube, and at least one cooling gas supply emanating in the cooling chamber. The core tube may have an elongated circumferential wall extending in a longitudinal direction, and the core tube may be configured to accommodate wafers for processing in the vertical batch furnace. The outer casing may extend around the core tube and may comprise a heating element for applying a thermal treatment to wafers accommodated in the core tube. The cooling gas supply may comprises at least one cooling gas supply opening which is arranged such that the cooling gas enters the cooling chamber with a flow direction which is substantially tangent to the circumferential wall.

There may also be provided a method for cooling a vertical batch furnace according to claim 16. More particularly, there may be provided a method comprising providing a vertical batch furnace 10 according to the description, and supplying a cooling gas in the cooling chamber 20 with a flow direction which is substantially tangent to the circumferential wall. The substantially tangent flow direction may include an angle with the longitudinal direction of the elongated circumferential wall 14 in the range of 90°±15° and may include an angle in the range of 0°±10° with a plane through a point of the circumferential wall that is closest to a said respective cooling gas supply opening and that is tangential to the circumferential wall.

For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught or suggested herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

Various embodiments are claimed in the dependent claims, which will be further elucidated with reference to an example shown in the figures. The embodiments may be combined or may be applied separate from each other.

All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE FIGURES

While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the invention, the advantages of embodiments of the disclosure may be more readily ascertained from the description of certain examples of the embodiments of the disclosure when read in conjunction with the accompanying drawings, in which:

FIG. 1 shows an example of the vertical batch furnace assembly according to the description;

FIG. 2 shows upside-down view of a top part of the outer casing of the example of FIG. 1 ;

FIG. 3 schematically shows an exploded perspective view of a detail of FIG. 2 ; and,

FIG. 4 schematically shows a cross sectional view of an example of an end part of a cooling gas inlet tube according to the description.

DETAILED DESCRIPTION OF THE FIGURES

In this application similar or corresponding features are denoted by similar or corresponding reference signs. The description of the various embodiments is not limited to the example shown in the figures and the reference numbers used in the detailed description and the claims are not intended to limit the description of the embodiments, but are included to elucidate the embodiments.

Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below. The illustrations presented herein are not meant to be actual views of any particular material, structure, or device, but are merely idealized representations that are used to describe embodiments of the disclosure.

As used herein, the term “wafer” may refer to any underlying material or materials that may be used, or upon which, a device, a circuit, or a film may be formed.

In the most general term the present disclosure may provide a vertical batch furnace assembly 10. The vertical batch furnace assembly 10 may comprise a core tube 12, an outer casing 16, a cooling chamber 20 bounded on a radial outer side by the outer casing 16 and on a radial inner side by the core tube 12, and at least one cooling gas supply emanating in the cooling chamber 20. The core tube 12 may have an elongated circumferential wall 14 extending in a longitudinal direction L, and the core tube 12 may be configured to accommodate wafers for processing in the vertical batch furnace assembly 10. The outer casing 16 may extend around the core tube 12 and may comprise a heating element 18 for applying a thermal treatment to wafers accommodated in the core tube 12. The cooling gas supply may comprise at least one cooling gas supply opening 26 which is configured such that the cooling gas enters the cooling chamber 20 with a flow direction which is substantially tangent to the circumferential wall 14. The substantially tangent flow direction may include an angle with the longitudinal L direction of the elongated circumferential wall 14 in the range of 90°±15°. The substantially tangent flow direction may include an angle in the range of 0°±10° with a plane through a point of the circumferential wall 14 that is closest to said respective cooling gas supply opening 26 and that is tangential to the circumferential wall 14.

With a flow direction of gas out of the gas supply opening 26 which is at least initially tangent to the circumferential wall 14, the cooling gas will not immediately flow along the longitudinal direction of the elongated circumferential wall 14, but instead will spread out in a tangential direction of the circumferential wall 14. Only after the cooling gas has spread out in the tangential direction of the circumferential wall 14, the cooling gas will flow along the longitudinal direction L of the elongated circumferential wall 14 as indicated with arrow F in FIG. 1 . By first distributing the cooling gas tangentially, the circumferential wall 14 is more uniformly cooled. In this way, no cold spots are formed, and the disadvantages associated with these so-called cold spots are prevented.

In an embodiment, of which an example is shown in exploded view in FIG. 3 , each cooling gas supply may comprise a cooling gas inlet tube 22 of which an end part 24 extends into the cooling chamber 20. Said end part 24, also shown in FIG. 4 , may be provided with the at least one cooling gas supply opening 26. Each cooling gas inlet tube 22 may be made of one piece. Each cooling gas inlet tube 22 may be made of a ceramic material. An axial end 28 of the cooling gas inlet tube 22 extending into the cooling chamber 20 may be closed off.

In the example shown in FIG. 4 , the cooling gas inlet tube 22 extends into the cooling chamber 20. The cooling gas inlet tube 22 may extend through an opening 44 in the outer casing 16. By having the axial end 28 of the cooling gas inlet tube 22 closed off, the cooling gas may be prevented from entering the cooling chamber 20 parallel to the longitudinal direction of the elongated circumferential wall 14. The end part of the shown cooling gas inlet tube 22 is provided with two cooling gas supply openings 26. Each supply opening is orientated such that cooling gas entering the cooling chamber 20 via said opening enters the cooling chamber 20 tangentially with relative to the circumferential wall 14. The cooling gas inlet tube 22 may be provided with a cam 46 arranged to cooperate with a corresponding recess 48 in the outer casing 16, which recess 48 is part of the opening 44 through which the cooling gas inlet tube 22 extends. The combination of the cam 46 on the cooling gas inlet tube 22 and the recess 48 in the outer casing 16 fixates the orientation of the cooling gas inlet tube 22 with respect to the outer casing 16 and thus also to the vertical batch furnace assembly 10 and the core tube 12. This may ensure that the cooling gas supply openings 26 will have the correct orientation with respect to the core tube 12 so that the cooling gas will enter the cooling chamber 20 having a flow direction which is substantially tangent to the circumferential wall 14.

The cooling gas inlet tube 22 may be heated during the treatment of the wafers in the core tube 12. The supplied cooling gas may lead to a big drop in temperature of the cooling gas inlet tube 22, when the cooling commences. This drop in temperature may lead to internal stress in the cooling gas inlet tube 22. By embodying the cooling gas inlet tube 22 as one integral part, there are no fragile joints in the cooling gas inlet tube 22 which may cause a breaking of the cooling gas inlet tube 22 caused by this internal stress. Preferably, each cooling gas inlet tube 22 is made of ceramic material. Ceramic material is able to withstand both high temperatures and large temperature fluctuations. This makes ceramic material very suitable for the cooling gas inlet tube 22.

In an embodiment, of which an example is shown in FIG. 2 , the at least one cooling gas supply 22 comprises a plurality of cooling gas supplies which are evenly spaced around the core tube 12. By evenly spacing the cooling gas supplies around the core tube 12 a uniform inflow of cooling gas along the elongated circumferential wall 14 may be obtained.

In an embodiment, of which an example is shown in FIG. 1 , the vertical batch furnace assembly 10 may further comprise at least one cooling gas discharge 30 comprising at least one discharge opening 31 to discharge the cooling gas from the cooling chamber 20. In operation, the emanated cooling gas may flow from the at least one cooling gas supply along the elongated circumferential wall 14 of the core tube 12 to the at least one cooling gas discharge 30.

The at least one cooling gas discharge 30 may comprises a plurality of cooling gas discharges 30 which are evenly spaced around the core tube 12. By evenly spacing the cooling gas discharges 30 around the core tube 12 a uniform outflow of cooling gas along the elongated circumferential wall 14 is obtained.

As shown in FIG. 1 , the at least one cooling gas supply may be arranged at or near a first longitudinal end 32 of the cooling chamber, and the at least one cooling gas discharge 30 may be arranged at or near a second longitudinal end of the cooling chamber 34. In this way the cooling gas will flow parallel to the longitudinal direction along the elongated circumferential wall 14 as indicated with the arrow F.

The vertical batch furnace assembly 10 may further comprise a cooling gas recirculation channel 36 extending from the at least one cooling gas discharge 30 to the at least one cooling gas supply 22. The cooling gas recirculation channel 36 may comprise a pressure increasing device 38, such as a fan or blower, and a heat exchanger 40 configured to cool the cooling gas in the recirculation channel 36. By recirculating the cooling gas, the cooling gas is re-used, which means no new cooling gas has to be supplied. This is especially advantageous when the cooling gas is not the ambient air, but e.g. concentrated nitrogen which has to be bought, and of which the supply can run out. Furthermore, by not constantly introducing new cooling gas into the cooling chamber 20, debris or pollution does not enter the cooling chamber 20 either. Also hazardous pollution originating from the cooling chamber or other parts of the vertical batch furnace assembly 10 are not emitted to the surroundings together with the cooling gas.

Preferably, the pressure increasing device 38 may be arranged downstream of the heat exchanger 40. It may be desired to have the pressure at the cooling gas supply opening 26 at a certain level. By having the pressure increasing device 38 arrange downstream of the heat exchanger 40, the pressure increasing device 38 needs less power to achieve a certain pressure at the cooling gas supply opening 26, as opposed to an arrangement wherein the pressure increasing device 38 is arranged upstream of the heat exchanger 40.

The configuration of the at least one cooling gas discharge 30 may be similar to the configuration of the at least one cooling gas supply, wherein the flow direction of the cooling gas within the cooling chamber 20 is reversible. The at least one cooling gas discharge opening may be configured such that, when the flow direction of the cooling gas within the cooling chamber 20 is reversed and the cooling gas discharge opening serves as a cooling gas supply opening 26, the cooling gas enters the cooling chamber 20 with a flow direction which is substantially tangent to the circumferential wall 14.

The cooling gas may cool the core tube 12 by absorbing heat from said core tube 12. When flowing in one direction, the cooling gas is coldest when entering the cooling chamber 20 and warmest when exiting via the cooling gas discharge 30. This means that part of the circumferential wall 14 closest to the cooling gas discharge 30 will be cooled to a lesser extent by the cooling gas than the part of the circumferential wall 14 which are closer to the cooling gas supply tubes 22. In order to increase the overall cool down speed of the elongated circumferential wall 14, it may be beneficiary to have the cooling gas also flow from the cooling gas discharge 30 towards the cooling gas supply. The cooling gas may then flow for a certain time from the cooling gas supply along the circumferential wall 14 to the cooling gas discharge 30 thereby primarily cooling part of the circumferential wall 14 nearest the cooling gas supply. After said certain time the flow direction may be reversed and the cooling gas may flow a certain time from the cooling gas discharge 30 along the circumferential wall 14 to the cooling gas supply 22 thereby primarily cooling part of the circumferential wall 14 nearest the cooling gas discharge 30. In this way the overall cooling efficiency of the cooling gas flow is increased.

In the example shown in FIG. 1 , this inversion of flow may be effected in that the inlet of pressure increasing device 38 may be connected to two suction parts 36 b of the recirculation channel 36. Each suction part 36 b may include a discharge valve 52 a, 52 b. An outlet of the pressure increasing device 38 may be connected to a pressure part 36 a of the recirculation channel 36. The supply part 36 a of the cooling gas recirculation channel 36 is split in two parts and each part may comprise diverter valve 42 a, 42 b. In use, only one of the suction parts 36 b may be operative transport cooling gas and the other one may be closed off by a the associated discharge valve 52 a or 52 b. By cleverly switching the diverter valves 42 a, 42 b and the discharge valves 52 a, 52 b the cooling gas may either be directed to the at last one cooling gas supply 22, and subsequently via the cooling chamber 20 to the at least one cooling gas discharge 30 or, alternatively, to the at least one cooling gas discharge 30, and subsequently via the cooling chamber 20 to the at least one cooling gas supply 22.

Apart from being functionally the same, the cooling gas discharge 30 may also be structurally the same as the cooling gas supply 22. This is advantageous for building said cooling gas discharge 30 and cooling gas supply 22, because only one type of part needs to be manufactured.

The present disclosure may also provide a method for cooling a vertical batch furnace. The method may comprise providing a vertical batch furnace 10 according to the description, and supplying a cooling gas in the cooling chamber 20 with a flow direction which is substantially tangent to the circumferential wall 14.

In an embodiment, the substantially tangent flow direction includes an angle with the longitudinal direction L of the elongated circumferential wall 14 in the range of 90°±15°.

In an embodiment, the substantially tangent flow direction includes an angle in the range of 0°±10° with a plane through a point of the circumferential wall that is closest to a said respective cooling gas supply opening 26 and that is tangential to the circumferential wall 14.

With an initial flow which is tangent to the circumferential wall 14, the cooling gas will not immediately flow along the longitudinal direction L of the elongated circumferential wall 14, but instead will be distributed in a tangential direction of the circumferential wall 14. Only after the cooling gas has been distributed in the tangential direction of the circumferential wall 14, the cooling gas will flow in the longitudinal direction L along the elongated circumferential wall 14. In this way there are no cold spots formed, and the disadvantages associated with these so-called cold spots are prevented.

Although illustrative embodiments of the present invention have been described above, in part with reference to the accompanying drawings, it is to be understood that the invention is not limited to these embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this description are not necessarily all referring to the same embodiment.

Furthermore, it is noted that particular features, structures, or characteristics of one or more of the various embodiments which are described above may be used implemented independently from one another and may be combined in any suitable manner to form new, not explicitly described embodiments. The reference numbers used in the detailed description and the claims do not limit the description of the embodiments, nor do they limit the claims. The reference numbers are solely used to clarify.

LEGEND

-   10—vertical batch furnace assembly -   12—core tube -   14—circumferential wall -   16—outer casing -   18—heating element -   20—cooling chamber -   22—cooling gas inlet tube -   24—end part (of the cooling gas inlet tube) -   26—cooling gas supply opening -   28—axial end (of the cooling gas inlet tube) -   30—cooling gas discharge -   32—first longitudinal end (of the cooling chamber) -   34—second longitudinal end (of the cooling chamber) -   36—cooling gas recirculation channel -   38—pressure increasing device -   40—heat exchanger -   42 a—diverter valve -   42 b—diverter valve -   44—opening (in the outer casing) -   46—cam -   48—recess -   52 a—discharge valve -   52 b—discharge valve -   L—longitudinal direction 

1. A vertical batch furnace assembly, comprising: a core tube having an elongated circumferential wall extending in a longitudinal direction, wherein the core tube is configured to accommodate wafers for processing in the vertical batch furnace assembly; an outer casing extending around the core tube and comprising a heating element for applying a thermal treatment to wafers accommodated in the core tube; a cooling chamber bounded on a radial outer side by the outer casing and on a radial inner side by the core tube; at least one cooling gas supply emanating in the cooling chamber, wherein the cooling gas supply comprises at least one cooling gas supply opening which is configured such that the cooling gas enters the cooling chamber with a flow direction which is substantially tangent to the circumferential wall; and a cooling gas recirculation channel extending from the at least one cooling gas discharge to the at least one cooling gas supply, the cooling gas recirculation channel comprising: a pressure increasing device; and a heat exchanger configured to cool the cooling gas in the recirculation channel, wherein the flow direction of the cooling gas within the cooling chamber is reversible.
 2. The vertical batch furnace according to claim 1, wherein the substantially tangent flow direction includes an angle with the longitudinal direction of the elongated circumferential wall in the range of 90°±15°.
 3. The vertical batch furnace according to claim 1, wherein the substantially tangent flow direction includes an angle in the range of 0°±10° with a plane through a point of the elongated circumferential wall that is closest to said respective cooling gas supply opening and that is tangential to the circumferential wall.
 4. The vertical batch furnace assembly according to claim 1, wherein the at least one cooling gas supply comprises a cooling gas inlet tube of which an end part extends into the cooling chamber, wherein said end part is provided with the at least one cooling gas supply opening.
 5. The vertical batch furnace assembly according to claim 4, wherein the cooling gas inlet tube is embodied as one integral part.
 6. The vertical batch furnace assembly according to claim 4, wherein the cooling gas inlet tube is made of a ceramic material.
 7. The vertical batch furnace assembly according to claim 4, wherein an axial end of the cooling gas inlet tube extending into the cooling chamber is closed.
 8. The vertical batch furnace assembly according to claim 1, comprising a plurality of cooling gas supplies including the at least one cooling gas supply, wherein the plurality of cooling gas supplies are spaced around the core tube.
 9. The vertical batch furnace assembly according to claim 1, wherein the at least one cooling gas discharge comprises a plurality of cooling gas discharges which are spaced around the core tube.
 10. The vertical batch furnace assembly according to claim 1, wherein the at least one cooling gas supply is arranged at or near a first longitudinal end of the cooling chamber, and the at least one cooling gas discharge is arranged at or near a second longitudinal end of the cooling chamber.
 11. The vertical batch furnace assembly according to claim 1, wherein the pressure increasing device is arranged downstream of the heat exchanger.
 12. The vertical batch furnace assembly according to claim 1, wherein the cooling gas recirculation channel comprises diverter valves and/or discharge valves to direct the cooling gas.
 13. A method for cooling a vertical batch furnace, comprising: providing a vertical batch furnace according to claim 1; and supplying a cooling gas in the cooling chamber with a flow direction that is substantially tangent to the circumferential wall.
 14. The method according to claim 13, wherein the substantially tangent flow direction includes an angle with the longitudinal direction of the elongated circumferential wall in the range of 90°±15°
 15. The method according to claim 13, wherein the substantially tangent flow direction includes an angle in the range of 0°±10° with a plane through a point of the circumferential wall that is closest to a said respective cooling gas supply opening and that is tangential to the circumferential wall. 